please help

4. (a). The common voltage output of power generators is 22 kV. A step-up transformer is needed to increase the voltage to 230 kV before transmission. What is the turn ratio of the transformer, Np/N? Can the same transformer be used to step down voltage? [4 marks ] (b). Explain why there would be no induced voltage across the secondary output of a transformer if the primary input is open? [4 marks]